package common.test;

import common.TreeNode;

public class BalanceTree {

    public boolean isBalanced(TreeNode root) {
        if (root == null) {
            return true;
        }
        return depth(root) != -1;
    }

    public int depth(TreeNode root) {
        if (root == null) {
            return 0;
        }
        int left = depth(root.left);
        int right = depth(root.right);
        if (left == -1 || right == -1 || Math.abs((left - right)) > 1) {
            return -1;
        }
        return Math.max(left, right) + 1;
    }
}
